The advanced OverTechnology humanity obtained from the crash of the Alien StarShip-1 lead to a great many scientific discoveries. Of those discoveries perhaps none was so profound as the concept of the Grand Cannon. The theory of the Grand Cannon was completed in March 2002 and construction on the first land-based installation began just two months later. The initial project site was the U.N. Military Headquarters in Alaska and construction began on a massive cannon six kilometers long buried deep underground. When activated, the Grand Cannon took but a few minutes to power and unleashed a massive energy blast utilizing the power of Earth’s gravity. The cannon was designed to unleash a beam many orders of magnitude more destructive than the firepower of entire fleets. Near the end of Space War One, the Grand Cannon was fired at the bulk of the Zentradi Bodol Main Fleet, a fleet of 4,795,122 ships. Although the ships of the Bodol fleet were far too numerous to be defeated even by the Grand Cannon, the cannon did succeed in destroying a large portion of the fleet, leaving the fleet at 4,000,000 ships after firing one continuous blast. The Grand Cannon is described as the largest class of heavy quantum reaction cannon ever built (Macross Chronicle 2E Technology Sheet 13A: Dimension Weapons)

A total of five Grand Cannon complexes were constructed. Four of these cannons were built on planet Earth (GC I in Alaska, GC II in the Australian Autonomous Region, GC III in Africa/Victorian Autonomous Region, and GC V in the Brazilian Autonomous Region) while GC IV was constructed on the Moon in the North Polar Region. Grand Cannon II in Australia was destroyed while still under construction in November 2005 by Anti-U.N. forces. The other complexes never saw completion. However, the other Grand Cannons III and V did shelter thousands of survivors during the annihilation of Earth's surface by the Bodol Fleet at the end of Space War I.